Haemostasis

Question 1

How does blood clot?

Answer 1

Vessel damage -> platelet adhesion (through platelet glycoproteins eg vwb factor, collagen, fibrinogen, factors 1A, 1B, 2A, 3A, 3B, 4, -> platelet activation (ADP and thrombin + epinephrine bind to make it sticky) -> platelet aggregation (platelets stick together through arachadonic acid (COX) into thromboxane A2 and so plug the hole) -> coagulation (scramblase flips membrane so phospholipids on the outside and allows fibrin net to form via clotting factors 8-12 to turn prothrombin into thrombin which acts to turn fibrinogen into fibrin)

Question 2

What factors influence if blood is hyper- or hypo- coaguable?

Answer 2

An increase or decrease in clotting factors, eg factors 8-12, prothrombin etc

Question 3

What are the main tests of coagulation?

Answer 3

Prothrombin time
Activated partial thromboplastin time
Thrombin time